Mitt Romney has a slight, 2-point edge over President Obama in Gallup's first "likely voter" estimate, the pollster said Tuesday.

Romney leads 49%-47% among those likely voters. Gallup reported.

However, Obama leads among registered voters by 49%-46% in the survey based on interviews conducted Oct. 2-8.

Both numbers are within the margin of error.

"Neither result provides a candidate with a statistically significant lead, but together they do underscore the competitive nature of the election and indicate that Romney at this point benefits from turnout patterns, given the five-point swing in his favor when the transition is made from registered voters to likely voters," reported Gallup.

The big apparent reason for Romney's surge: His performance in last week's debate against Obama.

Said the pollster: "All in all, if the election were held today, Gallup's analysis suggests that the race would be too close to call."

Other conclusions by Gallup:

"Several things are apparent from a careful analysis of Gallup Daily tracking of voters' views of the election. First, the registered voter trends suggest that Romney's initial gains from his strong performance in last week's debate may be short-lived.

"Second, Gallup's inaugural likely voter results suggest that Romney at this point appears to have a turnout advantage, meaning that Obama will need to develop a strong lead among all registered voters in order to be assured of winning the actual popular vote."

A new poll, a different view.

Mitt Romney now leads President Obama by 4 percentage points among likely voters after a strong debate performance last week, according to polling by the Pew Research Center.

The GOP presidential nominee has a 49% to 45% edge, Pew says. Last month, Obama had an 8-point advantage among those most likely to vote in the Pew survey.

Registered voters by more than 3-to-1 -- or 66% to 20% -- said Romney did a better job than Obama in their first presidential debate last week in Denver. Romney was generally viewed as more aggressive and forceful in their debate on the economy and domestic issues, while Obama sometimes lacked focus.

The Pew poll has a different finding than Gallup's daily tracking poll. In a seven-day rolling average Oct. 1-7, Obama led Romney among registered voters, 49% to 45%, according to Gallup.

Gallup, however, found that Romney pulled even with Obama in two days of surveys taken Thursday and Friday after the debate. Obama apparently did better over the weekend after the jobless rate for September went below 8%, as reported on Friday.